Abstract

The term operando was coined at the beginning of this Century to gather the growing efforts devoted to establishing structure-activity relationships by simultaneously characterizing a catalyst performance and the relevant chemistry during genuine catalytic operation (3 papers in 2002) . This approach is now widespread (more than 1,000 papers in 2023, Scopus); and at the junction where spectroscopy, materials science, catalysis and engineering meet. Engineering catalysis implies larger physical domains, and thus all sort of gradients.

The operando methodology requires a cell fit for in situ spectroscopy and performs like a catalytic reactor. It provides a tool to understand the actual state of the catalyst, its transformations during reaction and how these correlate with changes in catalytic performance. The presentation will address the study of supported oxide catalysts; the role of additives, support, hydration and reaction conditions on the states of supported catalysts. I will illustrate how operando methodology engages with complementary methodologies, such as computational chemistry, engineering and other spectroscopies. The transversal nature of the operando approach places it at the junction between fundamental catalytic chemistry and applied chemical engineering.

There is an additional value of Raman spectroscopy, since it provides also a tool for real time monitoring of reactions occurring in the liquid phase, that may in turn serve to control the reaction and to understand its reaction mechanism. For this, we are developing hardware and software tools to harmonize Raman spectra and the corresponding standards ., making spectra quantitatively interoperable and hence machine readable. This is critical for material and process monitoring and validation.

Banares, M.A., Guerrero-Perez, M.O., Fierro, J.L.G., Cortez, G.G., 2002. Raman spectroscopy during catalytic operations with on-line activity measurement (operando spectroscopy): a method for understanding the active centres of cations supported on porous materials. J Mater Chem 12, 3337–3342. https://doi.org/10.1039/b204494c

Bañares, M.A., Wachs, I.E.E., 2002. Molecular structures of supported metal oxide catalysts under different environments. Journal of Raman Spectroscopy 33, 359–380. https://doi.org/10.1002/jrs.866

Guerrero-Pérez, M.O., Bañares, M.A., 2002. Operando Raman study of alumina-supported Sb-V-O catalyst during propane ammoxidation to acrylonitrile with on-line activity measurement. Chemical Communications 1292–1293. https://doi.org/10.1039/b202556f

Raquel Portela, Miguel A. Bañares, José Francisco Fernandez, María Fernández, Alberto Moure, Nicolas Coca, Enrique Lozano, James Thomson, Muhammad Faizan, et al., 2024. CWA 18133:2024 ECEN-CENELEC Raman Instrument Calibration and verification protocols, CWA 18133:2024 E.